Hi Daniel,
I rather like the South Pole. It is far more fascinating than the North Pole. Penguins are cute (just look at the Oscar winning documentary) and besides Antartica is owned by a bunch of Nations with the US owning only a small chunk. I like that concept.
"ice does NOT retreat during an ice age"
Wow. So the people in Northern Italy still live under several metres of ice huh? When I was last in Milan there was some snow around admittedly but not all that much and it melted pretty darn quick. Go back a measly 12,000 years and the ice would be there mid summer.
Glaciers retreat during ice ages. Ice disappears entirely from many places on the earth. That's why they call the warm bits interglacial periods - they are the bit between the major encroachment of glaciers. Actually that is a bit of a reach but it certainly holds true for ice.
I'm finding it interesting how much basic paleoclimatology seems to be missing from these last few bits of discussions on global warming.
I also think we have managed to wander well off the point. Global warming is a very short term thing. Looking back to before our ice age won't do anybody much good because the conditions were quite different then. Even looking at the transition around 11,000 years ago into this interglacial period doesn't seem that relevant to arguing about a current warming trend because there is nothing to study of a short term nature.
If there is global warming, the evidence will be in temperature changes (whether we can assume accuracy of the measurements is a different thing entirely). It might be in other fields as well but paleoclimatology really won't help. I don't even believe my field of interest, the transitions between glaciations and interglacial periods and their causes is all that relevant. We are not talking about a cooling of the planet that may flip us into a glaciation. Then transition study would be quite important. Global warming is the theory that the earth, already in a warm period within an interglacial period is getting hotter still. Then the theory is extended to say this is because of man's activities on the earth, specifically the generation of greenhouse gases.
But if the discussion is going to focus on paleoclimatology for a while, it seems to me that getting the basics right should be where anyone starts.
The Northern Hemisphere pack ice has been around for many millions of years, well before this ice age. The fact that so far ice cores have only been found to go back 800,000 years in the Antartic does not indicate that the Antartic was free of ice for any period in the last several million years, only that they have not managed to drill deep enough or in the right places to go back further than 800,000 years. And sheet ice can melt without the ground being exposed. If the sheet ice remains say around ten metres deep then no matter how much you look you will not find evidence of anything but when that first ten metres was formed.
The reason why there is 800,000 years of records is because in the Antartic, there are sections of the continent that have had layers of ice building up much like rings of a tree without being rethawed. That is actually an unusual phenominum.
None of this proves that there was not sheet ice continuously for several million years. The evidence that does exist suggests that sheet ice really has been around for 40 million years (although it might have melted completely off an on for a few million of those years). Oh, and the reason for the appearance of the ice 40 million years ago had little to do with climate change and a whole lot to do with the Antartic continent actually approaching the South Pole and staying around that region.
It seems in this argument, the fact that the Poles are hellishly cold places simply because almost no solar radiation reaches them even mid summer (not visible light because I'm the first to admit how much glare that ice can give off).
No matter how hot the period in the earth's history from well before the extinction of dinosaurs, ice caps have been around. It is the extent of snow and ice coverage that waxes and wanes. For the north pole, this means pack ice and thus finding old ice is not an option.
On this there is substantial geologic evidence. It is easily found in even basic text books on the subject.
Richard
